Lactic acid bacteria are a kind of microorganisms that can ferment carbohydrates to produce lactic acid, and are currently widely used in the fermented food industry. In recent years, with the excellent role of lactic acid bacteria in the food industry and probiotic functions, their microbial metabolic characteristics have also attracted more attention. The lactic acid bacteria (LAB) are easily identified as Gram positive bacteria, non-respiring, non-spore forming, cocci or rods. As a fermentation strain, lactic acid bacteria should have several important metabolism characteristics, such as the ability to produce acid and aroma, the ability to hydrolyze protein, the ability to produce viscous exopolysaccharides and the ability to inhibit bacteria. In this review, the metabolic characteristics of lactic acid bacteria and its application in food industry were reviewed from the aspects of degradation. Lactic acid is the major end product of the fermentation of carbohydrates, though some fermentation produces other substances in addition to lactic acid. Fermentation of sour dough bread, sorghum beer, milks, cassava (to produce gari and fufu), ogi, kenkey, injera, obiolorare all examples of African fermented foods involving lactic acid bacteria. The major genera of lactic acid bacteria include the Lactobacillus, Leuconostoc, Pediococcusand Streptococcus species and even though a few more have been identified, they play a minor role in lactic fermentations. Lactic acid bacteria are usually found in decomposing plants and lactic products. Lactic acid is the major metabolic end product of the carbohydrate fermentation. LAB is a large group of fermentative, anaerobe aero-tolerant microorganisms that are usually present in the gut of humans and other animals, raw vegetables, meat and meat products, and cereal. In animals, their numbers may vary with the species, the age of the host, or the location within the gut. In the food industry, lactic acid bacterial strains are widely employed either as starter cultures or as non-starter lactic acid bacteria. Furthermore, owing to their probiotic properties, several LAB strains have found use as adjunctive cultures in foods and feed. Increasing commercial interest in functional food containing probiotics has increased scientific interests in these products. Lately, the researches in food biotechnologies have centered on careful isolation and selection of strains of Lactobacillus having antimicrobial properties that might both ensure the microbiological safety of the food as well as bring benefits to the consumer`s health. One of the anxieties which have evolved over the use of LAB as starter cultures, however, is resistance to antibiotics. Antibiotics are one of the great discoveries against bacterial infections. Unfortunately, bacteria can fight back by being resistant to antibiotics. From a human perspective, resistance to antibiotics is an undesirable ability of microorganism. Antibiotic resistance is the ability of a microorganism to remain unaffected by an antibiotic. When a microorganism becomes antibiotic-resistant, it is difficult to eliminate the infection caused by these microorganisms if and when it happens. Microorganisms can become resistant to antibiotics either by inactivating the drug, by altering the target site, by altering the metabolic pathway, or by reducing drug accumulation. In recent times, antibiotic resistance in bacteria has become a public concern issue. This is because a patient could develop antibiotic resistance by contacting a resistant microorganism or the emergence of a microorganism in the patient’s body when treatment with antibiotic begins. Even though a health beneficial microorganism such as LAB with antibiotic resistance may have the advantage of not being affected by the antibiotic when a consumer takes it together with the antibiotic, however, such an organism with antibiotic resistance could eventually become an opportunistic pathogen. This could be highly detrimental, to the infected host and the transfer of antibiotic resistant genes from the health beneficial food LAB to food pathogens may occur. Some species of LAB commonly used in the food industry or naturally occurring in raw food materials have been found to be resistant to glycopeptides antibiotics. Genes conferring resistance to several antimicrobials (including chloramphenicol, erythromycin, streptomycin, tetracycline, and vancomycin) located on transferable genetic elements (plasmids and transposons) have already been characterized in lactococci, and lactobacilli, from foods. The frequency of spontaneous mutation to kanamycin and streptomycin was reported to be very high for an appreciable number of lactobacilli. Currently, there are lots of data on the prevalence of antibiotic resistance and the mechanisms implicated in clinical bacteria. It is therefore important that strains intended for use in the food systems should also be carefully examined for antimicrobial susceptibility/resistance. Kunu-zaki is a traditional beverage made from spontaneously fermenting cereals. The beverage originated from Northern Nigeria but has found wide acceptability in all parts of the country. Cereals used for kunu-zaki include sorghum, millet or maize in non-composite proportions. Regardless of the cereal used, kunu-zaki wild fermentation is largely dominated by Lactic acid. The spontaneous fermentation production process however usually results in kunu-zaki of inconsistent quality from batch to batch of each production. The use of starter cultures, which would produce a uniform fermented kunu-zaki product quality remains yet unexplored. Yet this drink has become very popular in a country referred to as the most populous African nation. The hypothesis behind this present work therefore is that it would be possible to select strains with antimicrobial properties which can be used as starter cultures for kunu-zaki. The aim of this current study was to evaluate the antibiotic reaction pattern and the adhesion ability of antimicrobial homo-fermenting LAB strains present in fermenting slurries of kunu-zaki. This would be helpful in determining if the LAB would be affected if a kunu-zaki drinker is on antibiotic therapy. The information obtained from this study could contribute to the potential use of these LAB isolates in the food and pharmaceutical industries.
Author(s) Details:
O. Oluwajoba
Department of Microbiology, Federal University of Technology, Akure, Nigeria. And Department of Biological Science, Yaba College of Technology, Yaba, Lagos, Nigeria.
A. Akinyosoye
Department of Microbiology, Federal University of Technology, Akure, Nigeria.
O. Oyetayo
Department of Microbiology, Federal University of Technology, Akure, Nigeria.
Recent Global Research Developments in Lactic Acid Bacteria: Key Functional Starter Cultures in Food Fermentation
Traditional and New Microorganisms in Lactic Acid Fermentation of Food: This review discusses both traditional and new microorganisms involved in lactic acid fermentation. It highlights the health-promoting effects of fermented foods due to probiotic microorganisms and innovative methods using probiotics for functional foods [1] .
Recent Biotechnological Trends in Lactic Acid Bacterial Fermentation: This article explores various LAB strains used in the food industry, their metabolic pathways, and their applications in producing fermented foods like yogurt, cheese, and bread. It also covers advancements in metabolic engineering and synthetic biology for enhancing LAB functionalities [2] .
Recent Advances in Lactic Acid Production by Lactic Acid Bacteria: This review summarizes recent developments in lactic acid production, including strain modification technologies, the use of low-cost raw materials, and future prospects for the lactic acid industry [3] .
Lactic Acid Bacteria as Starter Cultures: An Update in Their Metabolism: This article provides insights into the genetics, molecular biology, and biochemistry of LAB. It discusses the commercial applications of starter, functional, bio-protective, and probiotic cultures [4] .
Lactic Acid Bacteria in Food Fermentation: Current Trends and Future Prospects: This review focuses on the role of LAB in food fermentation, their health benefits, and the latest trends in using LAB for developing new fermented food products [5] .
References
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- Raj, T., Chandrasekhar, K., Kumar, A.N. et al. Recent biotechnological trends in lactic acid bacterial fermentation for food processing industries. Syst Microbiol and Biomanuf 2, 14–40 (2022). https://doi.org/10.1007/s43393-021-00044-w
- Tian, X., Chen, H., Liu, H. et al. Recent Advances in Lactic Acid Production by Lactic Acid Bacteria. Appl Biochem Biotechnol 193, 4151–4171 (2021). https://doi.org/10.1007/s12010-021-03672-z
- Bintsis, T. (2018). Lactic acid bacteria as starter cultures: An update in their metabolism and genetics. AIMS microbiology, 4(4), 665.
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